Anhydrous ammonia delivery systems are commonly used to place large amounts of nitrogen in the soil. A tractor towed implement known as a tool bar has knives to open the soil, followed by disks to close the soil over the opened knife cut. Anhydrous ammonia (NH3) is placed in the soil by towing a tank of NH3, referred to as a nurse tank, behind the tool bar and flowing the NH3 through a delivery control system mounted on the tool bar to individual hoses attached to each of the knives used to open the soil. The NH3 flows through and is controlled by the delivery control system on the tool bar and into each of the hoses attached behind the tool bar knives. The liquid NH3 is thereby deposited deep in the soil and immediately covered over by the trailing disk. Over time, the nitrogen contained in the liquid NH3 is adsorbed into the soil and made available for the next crop.
An NH3 distribution system typically has three elements. The first is the meter for measuring the NH3 flowing through the delivery control valve. The second is the delivery control valve. The third is the distributor(s) for breaking the large flow line into multiple flow lines which will deliver the NH3 to each knife.
The operating characteristic of a distributor is such that once a travel speed and distribution rate has been established, the pressure at the distributor, known as back pressure, should be a stable value such that clogging of one or more of the knives does not occur. This back pressure is typically monitored with a large gauge attached to the distributor.
When conditions such as soil temperature and moisture content are right for placing NH3 in the soil, it is imperative that the NH3 be distributed as fast as possible due to the size of most farms and the ever changing soil conditions. This leads to delivery systems with very wide tool bars with many knives. Depending on the desired delivery rate and the width of the tool bar, multiple distributors may be used for a single delivery control system or multiple delivery control systems having one or more distributors may be used. When the NH3 delivery application is in process, the back pressure at all of the distributors should be relatively equal providing there is no blockage at one or more of the delivery hoses. It would be desirable to monitor all of the backpressures simultaneously to detect system malfunction and/or delivery hose clogging which could lead to a serious uneven distribution of NH3 to the field. In the case of multiple or in some cases single distributors, monitoring the back pressure is difficult if not impossible due to the distance of the gauges from the operator in the cab, which can be as much as 40 feet, not to mention the difficulty with the operator driving and turning around repeatedly to try and monitor back pressures at the tool bar.
The disadvantages of the prior art are overcome by the present invention, and an improved NH3 distributor back pressure monitoring system and method are hereinafter disclosed.